package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;

@Component
@Slf4j
public class CacheClient {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    public void set(String key,Object value,Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicalExpire(String key,Object value,Long time, TimeUnit unit){

        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        redisData.setData(value);
        //写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R,ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time, TimeUnit unit
    ){
        String key = keyPrefix +id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(json)){
            return JSONUtil.toBean(json, type);
        }
        //判断是否为空值
        if(json != null){
            //返回错误信息
            return null;
        }
        R r = dbFallback.apply(id);
        if (r==null) {
            stringRedisTemplate.opsForValue().set(key,"",2L,TimeUnit.MINUTES);
            return null;
        }
        this.set(key,r,time,unit);
        return r ;
    }


    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    //逻辑过期解决缓存击穿
    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix,ID id,Class<R> type,Function<ID,R> dbFallBack,Long time, TimeUnit unit)
    {
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(json)){
            return null;
        }

        //命中，需要把json反序列化为对象
        RedisData bean = JSONUtil.toBean(json, RedisData.class);
        JSONObject shop1 = (JSONObject) bean.getData();
        R r = JSONUtil.toBean(shop1, type);
        LocalDateTime expireTime = bean.getExpireTime();
        //反序列化结束判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //未过期，直接返回
            return r;
        }
        //已过期，需要缓存重建
        //缓存重建
        //获取互斥锁
        String localKey = RedisConstants.LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(localKey);
        //判断是否获取锁成功
        if (isLock) {
            //成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //重建缓存
                    //先插数据库
                    R r1 = dbFallBack.apply(id);
                    //写入redis
                    this.setWithLogicalExpire(key ,r1,time,unit);

                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(localKey);
                }
            });

        }
        //失败，返回店铺信息
        return r;
        //


    }
    private boolean tryLock(String key){
        Boolean b = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(b);
    }

    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }




}
